The research proposed in this grant application is a continuation on our studies of the ultrastructural features of lymphoreticular tissues in man and animals and the correlation of these features with biological, functional, and/or other characteristics of these tissues. There is particular interest in studying the murine myeloma cell system which, although neoplastic, possesses many of the characteristics of normal plasma cells. It is proposed to study long term cultures of these cells in order to relate the ultrastructural features to other characteristics which are persistent or may be modified with time in culture and experimental conditions. In particular, it is planned to study non-oncogenic forms of these tumor cells as these develop spontaneously in vitro. It is planned to evaluate ultrastructural features, functional characteristics such as globulin synthesis, growth characteristics, and antigenicity. The response of the host to the oncogenic or non-oncogenic cells at the histologic level and in terms of humoral and cellular immunological responses will also be evaluated. The ultrastructural characteristics of the membranes will be examined by routine methods and after freeze-etch procedures. Protease and neuraminidase treatment as well as ruthenium red staining will be used to compare oncogenic and non-oncogenic cells.